1. Field of the Invention
The present invention relates to optical ports and optical connection components used therein for optically coupling fibers such that an optical signal traverses the connection between the fibers. More particularly, the present invention relates to a system and method for inspecting optical ports for occlusions that might impede the optical signal.
2. Description of Related Art
As is known in the art, optical signals can be transmitted over optical fibers from location to location. Each optical fiber is optically connected or coupled to other fibers and/or optic processing equipment using optical components such as connector, adapters, optical ports and the like. At an optical connection, a pair of optical fibers transmits and receives optical signals across coupling surfaces formed at the termination end of the respective fibers. Optical connections have long been known as a primary source of signal degradation due to poor coupling characteristics such as misalignment of the optical axes, excessive spacing between coupling surfaces and contaminants which occlude or partially occlude the optical signal.
Normally, an optical connection takes the form of an adapter that engages a pair of optical connectors. The adapter, usually having a female-to-female connection, mates with the optical connectors, usually being a male connection. Each male optical connector secures the coupling surface of the fiber in a predetermined position and the adapter engages the optical connectors at a predetermined position such that the fibers are optically coupled to each other. Dust, dirt, pollen and other airborne contaminates often present a problem for transmitting optic signals because they are often introduced at the optical connections. In addition to the contaminants mentioned above, streaks from alcohol, acetone, oil stains and residual films can present a problem for optical transmissions. Once present, these contaminates degrade the optical signal, sometimes to a point where the transmission is completely obstructed. Inspecting optical fiber connections has been a continual problem in the telecommunications industry due to the minute cross-sectional size of the coupling surface to be inspected and the additional difficulty in accessing the recessed coupling surfaces. Rarely can contaminants be detected using the naked eye, therefore fiber microscopes have become popular for inspecting optical fiber connections.
Hand-held fiber microscopes presently known in the art are used for such inspections. These fiber microscopes allow an operator to peer into an eyepiece and directly view a coupling surface. Fiber microscopes include magnification and focusing optics for magnifying the coupling surface of a fiber while disposed on an optical fiber connector. In use, an operator normally positions the fiber coupling end of a fiber in the optical path of the uptake optics of the microscope and then peers into an eyepiece to examine the fiber coupling surface. Steadying the fiber microscope for accurately visualizing the fiber coupling surface is often difficult due to the high degrees of magnification necessary to examine the coupling surface in detail. Therefore, many fiber microscope models also come equipped with special adapter caps that easily attach to the uptake optics of the fiber microscope and which engage a particular type of male optical connector.
While this system works well for male optical connectors, problems occur when a male connector is engaged in an adapter and cannot be disengaged for inspection. This is the case with optical ports, especially bulkhead ports where a patch fiber is connected to an inaccessible side of a bulkhead adapter. Currently, in situ inspections are impossible because fiber microscopes cannot resolve an optical coupling surface mated to an adapter. The normal method for inspecting a coupling surface using a fiber microscope is to disengage the optical connector from the adapter and then inspect the optical connector separately. Current fiber microscope models are simply too big to be inserted into most adapters. Presently available optical fiber microscopes cannot be used to inspect crucial portions of any female fiber component, such as optic ports or miniature optical sleeves.
Furthermore, the area of the aperture opening of many adapters has been reduced. This is especially true for high density matrix port and block optical port styles where the entry area is condensed to make space for more optical connection in an equivalent area, thereby making inspection by current techniques even more difficult. Presently, several fiber scopes are available, however, the inspection head (encasing the lens and light shaft) and borescope insertion are large (more than xc2xc inch in diameter) such that it is impossible to access high density port such as MU, MT, LC and LX component types on optical cross connect, optical ultrabroadband DACS unless neighbor fiber connectors are removed.
Another problem facing the telecommunications industry is the current trend of component manufacturers equipping optical components with shutters. Both connector and adapters are currently equipped with shutters. Optical ports with shutters, such as E2000 (available from and trademarked by Diamond S.A.), LX.5 (available from and trademarked ADC Telecommunications, Inc., Minneapolis, Minn.) make visual inspection even more problematic because the coupling surface is protected by a shutter. Shutters can be affixed to a component externally, or in the case of some types of adapters, internally and recessed from the threshold of the adapter. In more advanced optical components, these shutters are part of a shutter system which cannot be actuated manually without great difficulty for the operator. With respect to these components, even if the fiber microscope""s size did allow for entry into the adapter, the target surface would remain hidden from view by the shutter.
A final problem associated with visually inspecting optical components is that moderate power lasers are used to drive the optical signal. Whenever an operator peers into an optical port, care should be taken to avoid the laser beam etching the operator""s retina. Laser sources have auto shut-off options; however, intermediate passive and active components, such as patch panels and optical cross-connect ports, do not have such options. There presently exists a great danger to the vision of inspection personnel while the laser source is on.
Currently, there is no solution for the problems described above. If db losses are higher than expected for an optical port, the usual procedure is to pump dry air onto the optical port hoping to free foreign particles from the coupling surface. However, this assumes that contaminants are actually present. Since visually inspecting the optical port is impossible, foreign particles may or may not be present Once the coupled surface has been sufficiently flooded with dry air, the circuit db losses are compared to the previous results. If db losses are reduced, then the process was a success and is repeated until no further db gain can be achieved. Otherwise, the complete board is replaced. Once removed and sent for maintenance, savvy technicians typically open the module case to access the internal optical patch fibers, disengage the optical connectors and inspect the connectors using a fiber microscope as described above. Because optical card failure is so often rooted with the optical connection to the card, it behooves technicians to inspect the optical ports prior to performing any more complex diagnostics on the card.
The present invention relates to a system and method for in situ inspection of optical ports for occlusions that might impede an optical signal. The present invention utilizes a mini-borescope of the type having a borescope insertion tube of less that two millimeters in diameter. The mini-borescope may utilize a video camera for capturing images of the target and adjustably magnifying the target image for display. In addition, one of a plurality of component type optical adapters is coupled to the mini-borescope insertion tube. Each particular type optical adapter allows the insertion tube to be inserted and aligned to a corresponding type of optical component, for instance, if the optical adapter is an SC-type male connector, then the insertion tube will be readily accepted by an SC-type female adapter. Also included in the optical adapter is a protective sleeve which surrounds a portion of the mini-borescope insertion tube. The protective sleeve provides the insertion tube with added rigidity, thereby lessening the likelihood of accidentally bending the tube during insertion. Optical adapters may also cooperate with component shutter systems for actuating protective shutters during engagement of the optical adapter, thereby exposing the coupling surface without manual intervention.